package com.fjc.security;

import org.apache.tomcat.util.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
/**
 * Created by fjc on 2018/7/9.
 */
public class RSAUtil {
    public static void main(String[] args) throws Exception{
//        Map<String, Key> keyMap = initKey();
//        String publicKey = getPublicKey(keyMap);
//        String privateKey = getPrivateKey(keyMap);

        String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCukkeTS1QnLB65tR90sgwc1jDenKh0xfiYO/3bVUjxyTC1ar5bE/UozhGpwG11+BygazLKP8STATy/i957hj7tpTd0VJdC30war99rcrTK4ozhnZCatd2Fz2cfwVpT7tu4SLIeFXVqYHYIhidnd0Hl9Dn1I4vLUsDmQyyecF7hlwIDAQAB";
        String privateKey = "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";

        System.err.println("公钥: " + publicKey);
        System.err.println("私钥： " + privateKey);

//        System.err.println("公钥加密——私钥解密");
//        String inputStr = "abc";
//        byte[] encodedData = encryptByPublicKey(inputStr, publicKey);
//        byte[] decodedData = decryptByPrivateKey(encodedData,
//                privateKey);
//        String outputStr = new String(decodedData);
//        System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);

        System.err.println("私钥加密——公钥解密");
        String inputStr = "sign";
        byte[] data = inputStr.getBytes();
        byte[] encodedData = encryptByPrivateKey(data, privateKey);
//        System.out.println("加密后：" + new String(encodedData));
        byte[] decodedData = decryptByPublicKey(encodedData, publicKey);
        String outputStr = new String(decodedData);
        System.err.println("加密前: " + inputStr + "\n\r" + "解密后: " + outputStr);
    }

    public static final String KEY_ALGORITHM = "RSA";
    public static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    private static final String PUBLIC_KEY = "RSAPublicKey";
    private static final String PRIVATE_KEY = "RSAPrivateKey";

    public static byte[] decryptBASE64(String key) {
        return Base64.decodeBase64(key);
    }

    public static String encryptBASE64(byte[] bytes) {
        return Base64.encodeBase64String(bytes);
    }

    /**
     * 用私钥对信息生成数字签名
     *
     * @param data       加密数据
     * @param privateKey 私钥
     * @return
     * @throws Exception
     */
    public static String sign(byte[] data, String privateKey) throws Exception {
        // 解密由base64编码的私钥
        byte[] keyBytes = decryptBASE64(privateKey);
        // 构造PKCS8EncodedKeySpec对象
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取私钥匙对象
        PrivateKey priKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 用私钥对信息生成数字签名
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(priKey);
        signature.update(data);
        return encryptBASE64(signature.sign());
    }

    /**
     * 校验数字签名
     *
     * @param data      加密数据
     * @param publicKey 公钥
     * @param sign      数字签名
     * @return 校验成功返回true 失败返回false
     * @throws Exception
     */
    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        // 解密由base64编码的公钥
        byte[] keyBytes = decryptBASE64(publicKey);
        // 构造X509EncodedKeySpec对象
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        // KEY_ALGORITHM 指定的加密算法
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        // 取公钥匙对象
        PublicKey pubKey = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(pubKey);
        signature.update(data);
        // 验证签名是否正常
        return signature.verify(decryptBASE64(sign));
    }

    public static byte[] decryptByPrivateKey(byte[] data, String key) throws Exception{
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 解密<br>
     * 用私钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPrivateKey(String data, String key)
            throws Exception {
        return decryptByPrivateKey(decryptBASE64(data),key);
    }

    /**
     * 解密<br>
     * 用公钥解密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] decryptByPublicKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据解密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        return cipher.doFinal(data);
    }

    /**
     * 加密<br>
     * 用公钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPublicKey(String data, String key)
            throws Exception {
        // 对公钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得公钥
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicKey = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal(data.getBytes());
    }

    /**
     * 加密<br>
     * 用私钥加密
     *
     * @param data
     * @param key
     * @return
     * @throws Exception
     */
    public static byte[] encryptByPrivateKey(byte[] data, String key)
            throws Exception {
        // 对密钥解密
        byte[] keyBytes = decryptBASE64(key);
        // 取得私钥
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        return cipher.doFinal(data);
    }

    /**
     * 取得私钥
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPrivateKey(Map<String, Key> keyMap)
            throws Exception {
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 取得公钥
     *
     * @param keyMap
     * @return
     * @throws Exception
     */
    public static String getPublicKey(Map<String, Key> keyMap)
            throws Exception {
        Key key = keyMap.get(PUBLIC_KEY);
        return encryptBASE64(key.getEncoded());
    }

    /**
     * 初始化密钥
     *
     * @return
     * @throws Exception
     */
    public static Map<String, Key> initKey() throws Exception {
        KeyPairGenerator keyPairGen = KeyPairGenerator
                .getInstance(KEY_ALGORITHM);
        keyPairGen.initialize(1024);
        KeyPair keyPair = keyPairGen.generateKeyPair();
        Map<String, Key> keyMap = new HashMap(2);
        keyMap.put(PUBLIC_KEY, keyPair.getPublic());// 公钥
        keyMap.put(PRIVATE_KEY, keyPair.getPrivate());// 私钥
        return keyMap;
    }
}
